As described in Patent Document 1, for example, an exhaust manifold is mounted in the exhaust system of an internal combustion engine. The exhaust manifold includes branch pipes, which are connected to exhaust ports of the cylinders, and a collecting pipe into which the branch pipes converge. A flange is formed on the distal portion of each one of the branch pipes. The exhaust manifold is fastened to the cylinder head with bolts engaged with bolt holes formed in the flanges and the cylinder head. The exhaust manifold is formed of cast steel.
The exhaust system of the engine includes a plate-like heat shielding member, which is a heat insulator for covering the exhaust manifold to suppress the occurrence of heat damage caused by the exhaust manifold. Patent Document 1 discloses a configuration in which the heat shielding member is fastened to the exhaust manifold by passing bolts through bolt holes formed in the surfaces of the branch pipes and the surface of the collecting pipe of the exhaust manifold. Patent Document 2 describes a configuration in which the heat shielding member is fastened to the exhaust manifold by means of bolts engaged with bolt holes formed in the flanges of the intake manifold. The bolt holes are separate from bolt holes employed to fasten the intake manifold to the cylinder head.